Displays with reduced driver circuit ledges

ABSTRACT

An electronic device display may have a color filter layer, a thin-film-transistor layer, and a layer of liquid crystal material. The display may have a display cover layer such as a layer of glass or plastic. Adhesive may be used to attach the upper polarizer to the display cover layer. The thin-film transistor layer may have a substrate with upper and lower surfaces. Thin-film-transistor circuitry may be formed on the upper surface. A display driver integrated circuit may be mounted to the lower surface or a flexible printed circuit and may be coupled to the thin-film-transistor circuitry using wire bonding wires. Through vias that are formed through the thin-film-transistor layer substrate may be used in coupling the thin-film-transistor circuitry to the display driver integrated circuit.

This application is a continuation of U.S. patent application Ser. No. 13/600,862, filed Aug. 31, 2012, which is hereby incorporated by reference herein in its entirety. This application claims the benefit of and claims priority to U.S. patent application Ser. No. 13/600,862, filed Aug. 31, 2012.

BACKGROUND

This relates generally to electronic devices, and more particularly, to electronic devices with displays.

Electronic devices often include displays. For example, cellular telephones and portable computers often include displays for presenting information to a user. An electronic device may have a housing such as a housing formed from plastic or metal. Components for the electronic device such as display components may be mounted in the housing.

It can be challenging to incorporate a display into the housing of an electronic device. Size and weight are often important considerations in designing electronic devices. If care is not taken, displays may be bulky or may be surrounded by overly large borders.

It would therefore be desirable to be able to provide improved displays for electronic devices.

SUMMARY

An electronic device may be provided with a display having upper and lower polarizers. The display may have a color filter layer, a thin-film-transistor layer, and a layer of liquid crystal material interposed between the color filter layer and the thin-film-transistor layer. The color filter layer and thin-film-transistor layer may be interposed between the upper and lower polarizers. The display may have a display cover layer such as a layer of glass or plastic. Adhesive may be used to attach the upper polarizer to the display cover layer.

The thin-film transistor layer may have a substrate such as a layer of glass with opposing upper and lower surfaces. Thin-film-transistor circuitry may be formed on the upper surface. A display driver integrated circuit may be mounted to the lower surface or may be mounted to a flexible printed circuit. Wire bonding wires may be used to couple the thin-film-transistor circuitry to a display driver integrated circuit on the lower surface or may be used to couple the thin-film-transistor circuitry to a flexible printed circuit to which a display driver integrated circuit has been mounted.

Through vias may be formed through the thin-film-transistor layer substrate. The through vias may be used in coupling a display driver integrated circuit to the thin-film transistor circuitry or may be used to couple the thin-film-transistor circuitry to a flexible printed circuit to which a display driver integrated circuit is mounted.

Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative electronic device such as a laptop computer with a display in accordance with an embodiment of the present invention.

FIG. 2 is a perspective view of an illustrative electronic device such as a handheld electronic device with a display in accordance with an embodiment of the present invention.

FIG. 3 is a perspective view of an illustrative electronic device such as a tablet computer with a display in accordance with an embodiment of the present invention.

FIG. 4 is a schematic diagram of an illustrative electronic device with a display in accordance with an embodiment of the present invention.

FIG. 5 is a cross-sectional side view of an illustrative display in accordance with an embodiment of the present invention.

FIG. 6 is a cross-sectional side view of an illustrative display having wire bond connections that have been used to interconnect thin-film-transistor circuitry on the upper surface of a thin-film-transistor layer with flexible printed circuit structures on the lower surface of the thin-film transistor layer in accordance with an embodiment of the present invention.

FIG. 7 is a cross-sectional side view of an illustrative display in which a driver integrated circuit has been mounted on the lower surface of a thin-film-transistor layer and in which wire bond connections have been used to connect thin-film-transistor circuitry on the upper surface of the thin-film-transistor layer to the driver integrated circuit in accordance with an embodiment of the present invention.

FIG. 8 is a cross-sectional side view of an illustrative electronic device having a display in which a flexible printed circuit bus is being used to connect a driver integrated circuit to traces on an upper surface of a thin-film-transistor layer and in which optically clear adhesive is being used to attach display layers to a cover glass layer in accordance with an embodiment of the present invention.

FIG. 9 is a cross-sectional side view of an illustrative display in which through vias pass from the upper surface to the lower surface of the thin-film-transistor layer and in which a display driver circuit is coupled to the vias using a flexible printed circuit in accordance with an embodiment of the present invention.

FIG. 10 is a cross-sectional side view of an illustrative display in which through vias pass from the upper surface to the lower surface of the thin-film-transistor layer and in which a display driver circuit is mounted to the vias on the lower surface in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

Electronic devices may include displays. The displays may be used to display images to a user. Illustrative electronic devices that may be provided with displays are shown in FIGS. 1, 2, and 3.

FIG. 1 shows how electronic device 10 may have the shape of a laptop computer having upper housing 12A and lower housing 12B with components such as keyboard 16 and touchpad 18. Device 10 may have hinge structures 20 that allow upper housing 12A to rotate in directions 22 about rotational axis 24 relative to lower housing 12B. Display 14 may be mounted in upper housing 12A. Upper housing 12A, which may sometimes referred to as a display housing or lid, may be placed in a closed position by rotating upper housing 12A towards lower housing 12B about rotational axis 24.

FIG. 2 shows how electronic device 10 may be a handheld device such as a cellular telephone, music player, gaming device, navigation unit, or other compact device. In this type of configuration for device 10, housing 12 may have opposing front and rear surfaces. Display 14 may be mounted on a front face of housing 12. Display 14 may, if desired, have a display cover layer or other exterior layer that includes openings for components such as button 26. Openings may also be formed in a display cover layer or other display layer to accommodate a speaker port (see, e.g., speaker port 28 of FIG. 2).

FIG. 3 shows how electronic device 10 may be a tablet computer. In electronic device 10 of FIG. 3, housing 12 may have opposing planar front and rear surfaces. Display 14 may be mounted on the front surface of housing 12. As shown in FIG. 3, display 14 may have a cover layer or other external layer (e.g., a color filter layer or thin-film-transistor layer) with an opening to accommodate button 26 (as an example).

The illustrative configurations for device 10 that are shown in FIGS. 1, 2, and 3 are merely illustrative. In general, electronic device 10 may be a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment.

Housing 12 of device 10, which is sometimes referred to as a case, may be formed of materials such as plastic, glass, ceramics, carbon-fiber composites and other fiber-based composites, metal (e.g., machined aluminum, stainless steel, or other metals), other materials, or a combination of these materials. Device 10 may be formed using a unibody construction in which most or all of housing 12 is formed from a single structural element (e.g., a piece of machined metal or a piece of molded plastic) or may be formed from multiple housing structures (e.g., outer housing structures that have been mounted to internal frame elements or other internal housing structures).

Display 14 may be a touch sensitive display that includes a touch sensor or may be insensitive to touch. Touch sensors for display 14 may be formed from an array of capacitive touch sensor electrodes, a resistive touch array, touch sensor structures based on acoustic touch, optical touch, or force-based touch technologies, or other suitable touch sensor components.

Displays for device 10 may, in general, include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable image pixel structures. In some situations, it may be desirable to use LCD components to form display 14, so configurations for display 14 in which display 14 is a liquid crystal display are sometimes described herein as an example. It may also be desirable to provide displays such as display 14 with backlight structures, so configurations for display 14 that include a backlight unit may sometimes be described herein as an example. Other types of display technology may be used in device 10 if desired. The use of liquid crystal display structures and backlight structures in device 10 is merely illustrative.

A display cover layer may cover the surface of display 14 or a display layer such as a color filter layer, thin-film transistor layer or other portion of a display may be used as the outermost (or nearly outermost) layer in display 14. For example, a color filter layer or thin-film transistor layer that is covered by a polarizer layer may form the outermost layer for device 10. A display cover layer or other outer display layer may be formed from a transparent glass sheet, a clear plastic layer, or other transparent member.

Touch sensor components such as an array of capacitive touch sensor electrodes formed from transparent materials such as indium tin oxide may be formed on the underside of a display cover layer, may be formed on a separate display layer such as a glass or polymer touch sensor substrate, or may be integrated into other display layers (e.g., substrate layers such as a thin-film transistor layer).

A schematic diagram of an illustrative configuration that may be used for electronic device 10 is shown in FIG. 4. As shown in FIG. 4, electronic device 10 may include control circuitry 29. Control circuitry 29 may include storage and processing circuitry for controlling the operation of device 10. Control circuitry 29 may, for example, include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Control circuitry 29 may include processing circuitry based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio codec chips, application specific integrated circuits, etc.

Control circuitry 29 may be used to run software on device 10, such as operating system software and application software. Using this software, control circuitry 29 may present information to a user of electronic device 10 on display 14. When presenting information to a user on display 14, sensor signals and other information may be used by control circuitry 29 in making adjustments to the strength of backlight illumination that is used for display 14.

Input-output circuitry 30 may be used to allow data to be supplied to device 10 and to allow data to be provided from device 10 to external devices. Input-output circuitry 30 may include communications circuitry 32. Communications circuitry 32 may include wired communications circuitry for supporting communications using data ports in device 10. Communications circuitry 32 may also include wireless communications circuits (e.g., circuitry for transmitting and receiving wireless radio-frequency signals using antennas).

Input-output circuitry 30 may also include input-output devices 34. A user can control the operation of device 10 by supplying commands through input-output devices 34 and may receive status information and other output from device 10 using the output resources of input-output devices 34.

Input-output devices 34 may include sensors and status indicators 36 such as an ambient light sensor, a proximity sensor, a temperature sensor, a pressure sensor, a magnetic sensor, an accelerometer, and light-emitting diodes and other components for gathering information about the environment in which device 10 is operating and providing information to a user of device 10 about the status of device 10.

Audio components 38 may include speakers and tone generators for presenting sound to a user of device 10 and microphones for gathering user audio input.

Display 14 may be used to present images for a user such as text, video, and still images. Sensors 36 may include a touch sensor array that is formed as one of the layers in display 14.

User input may be gathered using buttons and other input-output components 40 such as touch pad sensors, buttons, joysticks, click wheels, scrolling wheels, touch sensors such as sensors 36 in display 14, key pads, keyboards, vibrators, cameras, and other input-output components.

A cross-sectional side view of an illustrative configuration that may be used for display 14 of device 10 (e.g., for display 14 of the devices of FIG. 1, FIG. 2, or FIG. 3 or other suitable electronic devices) is shown in FIG. 5. As shown in FIG. 5, display 14 may include backlight structures such as backlight unit 42 for producing backlight 44. During operation, backlight 44 travels outwards (vertically upwards in the orientation of FIG. 5) and passes through display pixel structures in display layers 46. This illuminates any images that are being produced by the display pixels for viewing by a user. For example, backlight 44 may illuminate images on display layers 46 that are being viewed by viewer 48 in direction 50.

Display layers 46 may be mounted in chassis structures such as a plastic chassis structure and/or a metal chassis structure to form a display module for mounting in housing 12 or display layers 46 may be mounted directly in housing 12 (e.g., by stacking display layers 46 into a recessed portion in housing 12). Display layers 46 may form a liquid crystal display or may be used in forming displays of other types.

In a configuration in which display layers 46 are used in forming a liquid crystal display, display layers 46 may include a liquid crystal layer such a liquid crystal layer 52. Liquid crystal layer 52 may be sandwiched between display layers such as display layers 58 and 56. Layers 56 and 58 may be interposed between lower polarizer layer 60 and upper polarizer layer 54.

Layers 58 and 56 may be formed from transparent substrate layers such as clear layers of glass or plastic. Layers 56 and 58 may be layers such as a thin-film transistor layer and/or a color filter layer. Conductive traces, color filter elements, transistors, and other circuits and structures may be formed on the substrates of layers 58 and 56 (e.g., to form a thin-film transistor layer and/or a color filter layer). Touch sensor electrodes may also be incorporated into layers such as layers 58 and 56 and/or touch sensor electrodes may be formed on other substrates.

With one illustrative configuration, layer 58 may be a thin-film transistor layer that includes an array of thin-film transistors and associated electrodes (display pixel electrodes) for applying electric fields to liquid crystal layer 52 and thereby displaying images on display 14. Layer 56 may be a color filter layer that includes an array of color filter elements for providing display 14 with the ability to display color images. If desired, the positions of color filter layer 56 and thin-film-transistor layer 58 may be inverted so that the thin-film-transistor layer is located above the color filter layer.

During operation of display 14 in device 10, control circuitry 29 (e.g., one or more integrated circuits such as components 68 on printed circuit 66 of FIG. 5) may be used to generate information to be displayed on display 14 (e.g., display data). The information to be displayed may be conveyed from circuitry 68 to display driver integrated circuit 62 using a signal path such as a signal path formed from conductive metal traces in flexible printed circuit 64 (as an example).

Display driver integrated circuit 62 may be mounted on thin-film-transistor layer driver ledge 82 or elsewhere in device 10. A flexible printed circuit cable such as flexible printed circuit 64 may be used in routing signals between printed circuit 66 and thin-film-transistor layer 60. If desired, display driver integrated circuit 62 may be mounted on printed circuit 66 or flexible printed circuit 64. Printed circuit 66 may be formed from a rigid printed circuit board (e.g., a layer of fiberglass-filled epoxy) or a flexible printed circuit (e.g., a flexible sheet of polyimide or other flexible polymer layer).

Backlight structures 42 may include a light guide plate such as light guide plate 78. Light guide plate 78 may be formed from a transparent material such as clear glass or plastic. During operation of backlight structures 42, a light source such as light source 72 may generate light 74. Light source 72 may be, for example, an array of light-emitting diodes.

Light 74 from light source 72 may be coupled into edge surface 76 of light guide plate 78 and may be distributed laterally throughout light guide plate 78 due to the principal of total internal reflection. Light guide plate 78 may include light-scattering features such as pits or bumps. The light-scattering features may be located on an upper surface and/or on an opposing lower surface of light guide plate 78.

Light 74 that scatters upwards from light guide plate 78 may serve as backlight 44 for display 14. Light 74 that scatters downwards may be reflected back in the upwards direction by reflector 80. Reflector 80 may be formed from a reflective material such as a layer of white plastic or other shiny materials.

To enhance backlight performance for backlight structures 42, backlight structures 42 may include optical films 70. Optical films 70 may include diffuser layers for helping to homogenize backlight 44 and thereby reduce hotspots, compensation films for enhancing off-axis viewing, and brightness enhancement films (also sometimes referred to as turning films) for collimating backlight 44. Optical films 70 may overlap the other structures in backlight unit 42 such as light guide plate 78 and reflector 80. For example, if light guide plate 78 has a rectangular footprint when viewed in direction 50 of FIG. 5 (i.e., when viewed as a top view), optical films 70 and reflector 80 may have a matching rectangular footprint.

FIG. 6 is a cross-sectional side view of an illustrative configuration that may be used for the structures of display 14 when it is desired to minimize the width of the inactive border region of the display 14. As shown in FIG. 6, display 14 may have a ledge such as ledge 82 on thin-film-transistor layer 58 (i.e., a portion of layer 58 that is uncovered by color filter layer 56). The size of ledge 82 of thin-film-transistor layer 58 may be minimized by mounting driver integrated circuit 62 on flexible printed circuit 64.

Thin-film-transistor layer 58 may include an array of display pixels. The display pixels may be controlled by signals that are routed over a grid of intersecting gate lines and data lines. Each display pixel may contain electrode structures for applying an electric field to an associated portion of liquid crystal layer 52. Thin-film transistors may be provided in the display pixels to control the electric fields that are applied by the electrode structures. The thin-film transistors, gate lines, data lines, other conductive lines, and other thin-film circuitry (e.g., gate line driver circuitry) formed on the upper surface of thin-film-transistor layer 58 is shown as thin-film-transistor circuitry 106 of FIG. 6.

Circuitry 106 may be formed on a substrate such as substrate 108. Substrate 108 may be formed from a sheet of clear glass or plastic or other transparent dielectric layer. Substrate 108 may have opposing planar upper and lower surfaces. Thin-film-circuitry 106 may be formed on the upper surface of substrate 108. Thin-film-circuitry 106 may include conductive lines such as conductive gate lines and data lines and other conductive lines that are used in distributing signals on thin-film-transistor layer 58. Conductive lines on thin-film-transistor layer 58 (e.g., metal traces or other conductive materials that are formed as part of thin-film-transistor circuitry 106 on the upper surface of thin-film-transistor substrate 108) are shown as lines 96 in FIG. 6.

Display driver integrated circuits such as display driver integrated circuit 62 of FIG. 6 may be mounted on substrates such as flexible printed circuit 64. Flexible printed circuit 64 may be attached to the lower surface of thin-film-transistor layer substrate 108 as shown in FIG. 6 or may be mounted to other support structures within device 10.

Flexible printed circuit 64 may include one or more layers of conductive lines 100 such as metal traces. Conductive lines 100 may serve as signal lines that distribute signals between display driver integrated circuit 62 and thin-film-transistor circuitry 106. Conductive lines 100 may include parallel signal paths that form a signal bus. Each of conductive lines 100 may be coupled to a respective signal path such as one of wire bond wires 92.

Each wire bonding wire 92 may have opposing first and second ends. The first end of each wire bonding wire 92 may be coupled to a respective one of traces 100 in flexible printed circuit 64 using a respective wire bond connection 98. The second end of each wire bonding wire 92 may be connected to a respective one of traces 96 in thin-film-transistor circuitry 106 on the upper surface of thin-film-transistor layer substrate 108. Wire bonding wires (wire bonds) 92 may be formed using a wire bonding tool. During wire bonding operations, the wire bonding head of the wire bonding tool and/or thin-film-transistor layer 58 may be positioned so that wire bonds 92 extend from the upper surface of thin-film-transistor layer 58 to the lower surface of thin-film transistor layer 58 (e.g., the exposed lower surface of flexible printed circuit layer 64).

Black masking material 90 may be formed around the inactive periphery (border) of display 14 between color filter layer 56 and thin-film-transistor layer 58. Black masking material 90, which may sometimes be referred to as opaque masking material, may be formed from a polymer containing carbon black or other material that absorbs visible light. Black masking material 90 may be patterned to form a strip that serves as an opaque border running around the rectangular periphery of display 14 overlapping inactive display components (e.g., display driver circuitry, a thin-film-transistor ledge, etc.) and helping to hide these components from view by a viewer such as viewer 48 of FIG. 5. Black masking material 90 may be deposited in a rectangular ring shape surrounding a central rectangular portion of display 14 that includes the display pixels for display 14.

Another illustrative configuration that may be used in forming a display with a reduced inactive border region is shown in FIG. 7. As shown in FIG. 7, display driver circuitry such as one or more display driver integrated circuits 62 may be mounted on the lower surface of thin-film-transistor layer substrate 108. Conductive lines 102 may be formed on the lower surface of thin-film-transistor layer substrate 108 (e.g., to form pads to which a flexible printed circuit cable may be attached). Wire bonding wires 92 may be used to form connections with display driver integrated circuit 62 directly at connections such as wire bond connection 98 and/or may be used to form connections with display driver integrated circuitry 62 by forming a connection such as connection 98′ with lower surface conductive lines 102. In configurations in which wire bonding wires 92 terminate on conductive lines 102, conductive lines 102 may be used to connect wires 92 to driver integrated circuit 62 (e.g., by using solder balls to flip-chip mount driver integrated circuit 62 to solder pads formed from conductive lines 102. Each wire bonding wire 92 may have a connection such as wire bond 94 of FIG. 7 with which that wire is connected to conductive lines on the upper surface of thin-film transistor layer 58.

As shown in the cross-sectional side view of FIG. 8, another way in which the size of thin-film-transistor layer driver ledge 82 may be minimized involves mounting a display driver integrated circuit 62 on flexible printed circuit 64 (e.g., using solder or other connections between the circuitry of integrated circuit 62 and conductive lines 100) and using conductive lines 100 in flexible printed circuit 64 to route signals between display driver integrated circuit 62 and conductive lines 96 and other thin-film-transistor circuitry 106 on the upper surface of thin-film-transistor substrate layer 108. Traces 100 may be coupled to traces 96 using conductive adhesive (anisotropic conductive film), welds, solder connections, board-to-board connectors, or other attachment mechanisms. Because display driver integrated circuit 62 need not be located on ledge 82 of thin-film-transistor layer 58, the size of ledge 82 (and therefore the width of the inactive border portion of display 14 in the vicinity of ledge 82) may be minimized.

Displays such as display 14 of FIG. 8 and other displays 14 for device 10 may have an optional display cover layer such as display cover layer 110. Display cover layer 110 may be formed from a layer of clear glass, a layer of transparent plastic, a layer of transparent ceramic, or other transparent material. The thickness of display cover layer 110 may be, for example, 0.1 to 5 mm (as examples).

If desired, optically clear adhesive such as adhesive 104 may be used to attach display cover layer 110 to the outermost surface of upper polarizer 54. When display cover layer 110 is attached to the layers of display 14 in this way, display cover layer 110 may exhibit a reduced likelihood of cracking during use of device 10, allowing the thickness of display cover layer 110 to be reduced. Display cover layer 110 may, if desired, be formed from a relatively hard material (e.g., glass) to resist scratching. Black masking layers 90 may be formed around the periphery of display cover layer 110 to block internal device structures such as driver ledge 82 from view by a user of device 10.

If desired, via structures may be used to reduce or eliminate the need for ledge 82 on thin-film-transistor layer 58. An illustrative configuration for display 14 in which the width of the inactive border for the display has been minimized by eliminating thin-film-transistor ledge 82 is shown in FIG. 9. As shown in FIG. 9, vias 112 may be formed between the upper and lower surfaces of thin-film-transistor layer 58. When routing signals through thin-film-transistor layer 58 in this way, ledge 82 may be eliminated.

Vias 112, which may sometimes be referred to as via structures, metal vias, or through vias, may be used to connect conductive lines in thin-film-transistor circuitry 106 such as conductive lines 96 to the circuitry of flexible printed circuit 64 (e.g., to conductive lines in flexible printed circuit such as conductive lines 100). Vias 112 may include holes that pass through substrate 108 and metal or other conductive material that fully or partly fills the holes. Solder, conductive adhesive, or other conductive materials may be used to couple the metal of vias 112 to the metal of conductive lines 100 in flexible printed circuit 64. Solder or other conductive materials may also be used in mounting driver circuitry such as display driver integrated circuit 62 to traces 100 of flexible printed circuit 64.

Flexible printed circuit 64 may include one or more bends such as right-angle bend 114 of FIG. 9. With the illustrative configuration of FIG. 9, flexible printed circuit 64 may have a portion that lies flat on the lower surface of substrate 108 and a portion that extends away from substrate 108 at a perpendicular angle (e.g., vertically downward in the arrangement of FIG. 9). This type of arrangement may allow display driver integrated circuit 62 to be mounted along the inner surface of a housing sidewall in housing 12 of device 10.

Vias 112 may be formed by drilling openings in thin-film-transistor substrate 108 (e.g., using laser etching or other hole formation techniques). Following the formation of openings in thin-film-transistor layer substrate 108, metal or other conductive material may be formed within the openings (e.g., using physical vapor deposition, chemical vapor deposition, electrochemical deposition, or other suitable fabrication techniques). If desired, vias 112 may be formed by embedding metal wires within thin-film-transistor layer 108 during glass formation operations.

As shown in FIG. 10, display driver integrated circuit 62 may be mounted directly to the lower surface of thin-film-transistor substrate layer 108. Solder, conductive adhesive, or other conductive material may be used in interconnecting the circuitry of display driver integrated circuit 62 to the metal of vias 112. Metal pads may be formed on the lower surface of substrate 108 (e.g., on vias 112 or connected to vias 112) and/or on display driver integrated circuit 62. Solder, conductive adhesive, or other conductive material may be interposed between the metal pads on substrate 108 and on display driver integrated circuit 62.

The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. 

What is claimed is:
 1. An organic light-emitting diode display comprising: a transparent display layer; a thin-film-transistor layer having a substrate with first and second opposing surfaces and thin-film-transistor circuitry formed on the first surface; and a display driver integrated circuit mounted to the second surface, wherein the transparent display layer overlaps the display driver integrated circuit, and wherein the substrate has conductive vias that pass through the substrate from the first surface to the second surface and that couple the thin-film-transistor circuitry to the display driver integrated circuit.
 2. The organic light-emitting diode display defined in claim 1 wherein the transparent display layer comprises a layer of dielectric material that at least partially overlaps the thin-film-transistor layer.
 3. The organic light-emitting diode display defined in claim 1 wherein the substrate comprises a plastic layer.
 4. The organic light-emitting diode display defined in claim 1, wherein the conductive vias comprise laser-drilled holes.
 5. The organic light-emitting diode display defined in claim 1, wherein the organic light-emitting diode display has an active area surrounded by an inactive border region, and wherein at least one of the conductive vias is formed in the inactive border region.
 6. The organic light-emitting diode display defined in claim 5, wherein the transparent display layer overlaps the conductive vias.
 7. The organic light-emitting diode display defined in claim 5 wherein at least one of the conductive vias overlaps the display driver integrated circuit.
 8. The organic light-emitting diode display defined in claim 7, wherein at least two of the conductive vias overlap the display driver integrated circuit.
 9. A display, comprising: a thin-film-transistor layer having a substrate with first and second opposing surfaces and having thin-film-transistor circuitry formed on the first surface; a flexible printed circuit having a first portion that is mounted to the second surface and a second portion that extends away from the second surface, wherein the first and second portions are connected by a bent portion of the flexible printed circuit; and a display driver integrated circuit mounted to the second portion of the flexible printed circuit, wherein the substrate has conductive vias that pass through the substrate from the first surface to the second surface and that couple the thin-film-transistor circuitry to the flexible printed circuit.
 10. The display defined in claim 9 wherein the second portion extends away from the second surface at an angle perpendicular to the second surface.
 11. The display defined in claim 9 wherein the flexible printed circuit has first and second opposing surfaces, wherein the first surface of the flexible printed circuit is mounted to the second surface of the substrate, and wherein the display driver integrated circuit is mounted to the second surface of the flexible printed circuit.
 12. The display defined in claim 9 wherein the display is an organic light-emitting diode display.
 13. The display defined in claim 9 wherein the substrate has a first peripheral edge between the first and second opposing surfaces, wherein the layer of dielectric material has a second peripheral edge, and wherein the first and second peripheral edges are aligned.
 14. The display defined in claim 9 wherein the substrate is a plastic layer.
 15. A display comprising: a thin-film-transistor layer having a substrate with upper and lower surfaces and thin-film-transistor circuitry formed on the upper surface; a layer of transparent dielectric material that overlaps the thin-film-transistor layer; and a display driver integrated circuit mounted directly to the lower surface, wherein the substrate has conductive vias that pass through the substrate from the upper surface to the lower surface and that couple the thin-film-transistor circuitry to the display driver integrated circuit, and wherein at least one of the conductive vias overlaps the display driver integrated circuit.
 16. The display defined in claim 15, further comprising: light-emitting structures that emit light through the layer of transparent dielectric material.
 17. The display defined in claim 15, wherein the display is an organic light-emitting diode display.
 18. The display defined in claim 15, wherein the substrate is a layer of plastic.
 19. The display defined in claim 15, wherein the display has an active area surrounded by an inactive border region.
 20. The display defined in claim 19, wherein the display driver integrated circuit is mounted directly to the lower surface in the inactive border region. 